US2270536A - Transmission drive cooling system - Google Patents

Description

Jan.20, 1942. C, K, LENNlNG 2,270,536

TRANSMISSION DRIVE COOLING SYSTEM ttornegs Y Jan. 20, 1942. .c. K. LENNING TRANSMISSION DRIVE COOLING SYSTEMy 2 sheets-sheet 2 Filed Feb. 17, 1940 Summon: Caffe/ few/.w1

l Gttornegs Patented Jan. 20, 1942 A TRANSMISSION DRIVE COOLING SYSTEM Carroll K; Lenning, Lansing, Mich., assigner to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application February 17, 1940, Serial No. 319,561

` 16 Claims. The invention relates to cooling .systems for -variable speed power transmissions, and more particularly to such motor drive installations having fluid turbine mechanisms for handling vehicle driving torque.

The object of the invention is to provide a cooling system for the fluid drive and for the variable speed transmission in which the heat generated by the slip of the fluid unit and by the rotation of power transmission parts is transferred through a common oil bath, pressure fed to radiation or exchange means subject -to constant ow of conducting air.

\A\ further object is to provide a power transmission assemblyequipped to yielda constant circulation of lubricating and cooling oil through a closed system containing in the path ofrow, a heat exchange means or member subject to constant air ow induced by the rotation of said means or member.

A specific object is to provide a power transmission assembly having incorporated therein a fluid flywheel arranged with respect to a rotatable drum member thereof adapted to act as a heat exchanger between a liquid flowing within said member and a constantly moving mass of air circulated outside of said drum member by its rotation. i

It is well known in this art to-provide special cooling means for fluid flywheel units in order tovextend the utility of such units in motor car, vehicle or boat installations. It is likewise a fact that because of space restrictions, and cost, the

advent of the fluid flywheel as a feature in motor carfassemblies has been retarded, in that adequate cooling for dissipation of slip-loss heat has required in the past a considerable expense for accessory cooling equipment.

The present invention therefore is directed toward a solution of the problem of maintaining a tolerable and reasonably uniform temperature condition in the fluid ywheel assembly and associated structure, by means of the features and objects noted above. Y

These and o'ther desirable objects of the in vention are obtained through the novel arrangement and construction and the improved combination with the accompanying drawings, in conjunction with the description of the following specication, in which;

Figure 1 is a vertical cross-section of a variable speed transmission assembly equipped with the invention, and shows an engine-connected drum connected through gearing to drive a duid turbine unit, commonly known as a uid iiywheel.

Figure 2 is a vertical sectional view of 'theJassemblyof Figure l taken at 2-2 of that figure. u

Figure 3 is a view taken from below of the enclosure pan for the engine flywheel housing.

Figure 4 is a part sectional view of one of the louvers of the air flow control system of the invention taken at l-,ll of Figure 2.

Referring to Figures 1 and 2, the engine ywheel casing lower jacket l0 is composed of sheet metal fastened to the bell housing 5 by appropriate means.

Louvers Il are in eject radial slots cut in the jacket l0. Their opening with respect to the normal direction of motion of the vehicle, and the normal rotation of the elements within the jacket I0, issuch that the air entering' the louvers Il is directed circumferentially into the space F immediately adjacent the spinning drum 9, inthe normal direction `of rotation of the latter. 4

From the well-known physical laws, .the skinfriction air drag effect is accentuated. by the arrangement described, the air blast caused by movement of the vehicle being converted from straight lineA flow to rotational flow within the space formed by the casing 5 and jacket i0.

Figure 2 describes the manner of cutting the radial louvers i l at thegengine side front p0rtion of the jacket lil, it being assumed that the normal hand of rotation ofthe engine connected drum 9 is clockwise when viewed from the front of the vehicle, as shown by the arrow on the shaft hub 2.

Because of the well-known effect of centrifugal force, the zone of greater air pressure within the jacket it is .at the periphery vof the drum 9, so that while the outside air below the power plant is flowing into the louvers il, more or less axially with respect to the power plant shaft center, upon passing inside of the jacket l0, it not only ,receives a rotational component,`but likewise a jacket lil and directed over the drum S therefore is given a sweeping movement having a rotational component and a centrifugal force eect.

The preceding explanation of the action of the ow of air has had to do with the incoming blast of cool air, and with what happens to it when it enters the primary circulation space F of the jacket i6.

The rear portion of jacket i0 is likewise louvered at I2, in the same manner that the front portion' is louvered at Il, as shown in Figure 3.

The louvers I2 open out from the space F between the drum 9 and thezjacket Hl and casing 5 so that the rotational force of the air mass Aradial component. The ow of air entering the invention, wherein the maximum ow effect is experienced, the vehicle is in motion.

It will be understood that on the .forward face of the jacket I0, the flow of outside air will create a pressure, and that on the rearward face, a suction. This differential of pressure is helpful, and adds to the ability of the spinning drum ,8 and the louvering system to establish a positive flow through the casing 5 and jacket I0, and thereby transfer heat from the drum 9 to the outside air.

When the vehicle is standing still, the louver-I ing system is enabled to function while the engine is rotating, due -to the drum skin-friction effect, but of course, without the assistance of the external air presure differential discussed above.V In still air, the rotation of the drum 9 generates an inflow in louvers II, I2, because of their aperture with respect to the direction of rotation. The spinning' mass of air inside the jacket I0 and casing 5 imparts a movement to the adjacent air masses in the mouths of the louvers II, which because of their shape,.tend

' Since the space G is maintained under posito exert a suction on the outside air. Simul.

taneously, the outward opening of louvers I2 on the rear of jacket I0, with respectto the direction of rotation of the inner air mass, allows an increment of that mass to escape.

Having an inow tendency on the front face, and an outow tendency on the rear face of the -Jacket I0 provides a net movement of air through the space F external to drum 9 within the jacket I0 and casing 5, thereby cooling the drum 9.

Figure 1 shows a fluid flywheel assembly associated with an engine flywheel I bolted to drum 9 splined to sleeve 2a. carrying annulus gear 20. The planetary gear unit of Figure 1 has no particular part in the present invention, but is shown in U. S. S. N. 124,283 to Kelley, filed February 5, 1937, now matured kas U. S. 2,176,138, as a part of the driving arrangement of that invention.

Rotor a of the fluid turbine durch is attached to the forward flange of hollow shaft 6- flxed'to carrier 2| of the gear unit. Sun gear '22 meshing with planets 23 on spindles supported in carrier 2|, is ixed/4 todbrake drum 24, having clutching engagement with carrier 2| through the agency of plates 25 and 26, actuated by fluidv pressure supplied to pistons 21 through appropriate control means, fed by pump 35, 36, to be described later.

central shaft 1 is mixed to fluid nywheei' tion to driving gearing nota part o this invention but shown in the above note Kelley patent. Likewise, hollow shaft 6 is joined with said latter driving gearing.

Sleeve 2l has afixed pump driving gear 3| meshing with gear 32 of vertical shaft 33, pinned rotor 4, and its farther end encompafssepconnec` to gear 35 of gear pump P immersed in the oil tive pressure, the oil in this space flows into the inner pocket or torus formed by the rotors 3 and 4, through the parting zone between the rotors. 1

Hub 4a of rotor 4 is drilled out radially at 44; and longitudinally at to accommodate valve check ball 46 and spring 41, the ball seating on seat 48 against the oil pressure existing in space connecting with the interior pocket formed by the rotors 3 and 4.

Central shaft 1 is centrally drilled at 5| and radially drilled at 5Ia open to annular space 5Ic connecting with exit passages for lubrication' As will be understood, the variations in speed of the engine will be repeated in variations in the speed, and in pressure generated by the pump.

Furthermore, changes in the operation of the variable speed gear, namely, actuation of the brake 28 on drum 24 and clutch 25A-26. will impart variable rotation tothe fluid yflywheel rotor 3. Since the pump P driven bythe engine maintains the fluid flywheel filled with transmission oil, and since the operation of the fluid flywheel causes inherent variations in the net pressure within the toroidal working space, the check valve 46 is operating a very considerable portion of the time, the strength of' spring 41 and the area of seat 48 being so taken with respect to the mean back pressure on the relief side, and the mean pump delivery pressure value; that a constant changing of the oil within the toroidal rotor pocket occurs.

The pump 35, 36, likewise lubricates under forced-feed the transmission gearing, forA example, through radial passage 5Ib feeding the space between shafts 6 and 1, and also drilling 53 in shaft 8, whence the gears of the unit 20-22-23, and 3| with the associated bearings not numbered, receive the flow, the spent-pressure oil dropping back into the sump S for recirculation. Heat generated in this portion of the assembly is spread out through the body of oil in sump ing 5, in part, and further dissipated by the positive air iiow through louvers- II, I2, passing over drum 9.

The large area of the drum 9 is a satisfactory air exposure surface, and the narrow oil space G within the drum 9 provides a reasonable thinness of oil film for vmaximum interchange of heat from film to drum.

Experience has taught that the fluid flywheel operating with liquid constantly confined tends to heat up to beyond the vapor point of customarily used liquids, and While the present invention is adaptable to such sealed units, it is of particular utility when combined with systems havingl positive, constant circulation of the driving liquid. This is true because the cooling factor required for proper operation is proportional for a considerable distribution of excess heat through the whole body of the sump oil, making the conduction-requirement for the mass ofair passed through the louvers Il, l2, `a readily provided one within the limits of good design for space allotment in the vehicle.

It should be remembered that the specific heat of oils such as used in motor car transmissionsis more than double that of an equal volume of air. With constant recirculation of .oil by the pump 35, 36, the oil pan a and casing 5 become,

useful secondary radiators for heat extracted from the uid flywheel torus. It is assumed, of

course, that general knowledge exists of the fact that the uid flywheel functions as a driving device because of the slip between its rotors. Energy loss due to slip must be dissipated in more or less direct ratio to the degree of slip, if the mechanism is to operate under stable heat con` flywheel system having no positive oil circula-k tion to assist in the disposal of excess heat, it may be necessary to utilize a somewhat different form of construction in which a larger degree of air ow may be had, such as by louvering similarlytheexternal casing 5 where it projects into the 'engine fan air stream beyond the contour of the engine itself.

It is not deemed necessaryto show this feature in the drawings, it being obvious that the ilywheel housing portion of the conventional motor car power plant is of larger general diameter than the width of the engineportion. Since the direction of ow of engine fan propelled airis customarily from the front of th'eengine toward the rear, where the flywheel housing is placed, the motion of air passing over the casing, even though warmed by the engine itself, still possesses heat absorption capacity. It is likewise within the purview of my invention to draw the engine cooling air over the flywheel and trans-'- mission housings before passing it through the heat exchange system; that is, in vehicle power plants placed at the rear, such as described in the drawings of the present specification, the drum 9 receives a constantl supply of oil from pump 35, 36, fed into the space G between it and the rotors. This oil must flow outward along the inner surface of the drum and along the external surfaces of the rotors. The space is relatively narrow in radial cross-section, so thaty the body of oil is spread out, facilitating the ex- U. S. 2,048,959 to RJIhompson, patented July 28, 1936. In this way the external air is fed first to the space adjacent the fluid flywheel of the present invention, adding to the ability of the system of the invention to extract heat from the uid iiywheel housing. A similar system is shown in U. S. 2,038,581 to Lent; patented April 28, 1936.

The dual cooling resulting from the construction of th'e version illustrated in thedrawings accompanying the present speci ation, by means of the constant circulation of lbrication oil'as a heat transfer' medium, and y means of the louver system described foi constant circulation of cooling air when theengine is running, is believed to constitute a-useful improvement in this art. Ordinary air flow cooling has been shown by others who-have utilized external ns on casnisms, an engine, a load shaft, a turbine drive ings-containing the fluid flywheel construction;

special systems for circulating coolant in the walls of such casings and throughvarious chambers have been described; and also engine cooling system water h'as been used for a driving fluid,'as well as sea water, in a boat" installation;

The present invention is simple. It is not complicated byl necessary connection with other cooling adjuncts, but is adaptable to augment the cooling effect required for any forml of uid flywheel construction, andhas, ofcourse, special adaptability to constructions wherein a con-v stant liquid now is maintained by other means. To make this-point explicit, as demonstrated by change of heat from the oil through the body of drum metal to the circulated air mass of the louver system. The heat exchange takes-place on a dynamic cycle rather than on a static cycle, for the constant' circulation of the oil film bringsin a fresh body of oil to the drum while th'e Acirculation of air is causing a renewedexternal heat exchange action. In both heat transfers, the exchange may be considered as a dyriamic, as compared with a staticprocess. In tracing the slip induced heat, it is considered as beginning at the parting zones between the rotors 3, 4, and from thence the oil ow extracts heat from the metal of the rotors themselves, carrying the fluid out through th'e check valve passages 65, B4, 5th, 5l to the lines leading to the sump where the unit heat charge of the oil is spread out over the whole body of sump oil.

This heat drop assists the cooling action tending to stabilize the quantity of heat passing through the pump-connected system to the cool-` ing space F between the rotors and the drum 9. Here the action is one of .positive heat extraction, whereas the action in thesump is one of spreading out, assisted, however by the heat dissipation ability of the transmission casing 5 and bottom pan 5a.

Actual experience with the system of the present invention has proven ,the beneficial result of the construction shown in the drawings. A definite acceleration of outward now of undesired heat occurs with this arrangement compared with the identical structure minus the air louvering system of the showing. The present invention is believed therefore to mark a measurable improvement in the cool- Fing facilities of power plants equipped with fluid ywheels, which improvementvis accentuated by the space limitations for power plants in modern motor vehicles. Furthermore, the simplicityA of the invention in construction and application .has

eliminated a very considerable cost factor in such power plants, otherwise requiring added features of oil coolers, with connections to engine or other cooling systems. Although the description herewith covers only one of the preferred forms of the invention, it

I is to be understood that numerous modifications may be made in the construction as disclosed. without departing from the spirit of the invention or from the scope of the appended claims.-

I claim: l. In uid turbine drive transmitting mecha'- i device adapted to transmit variable slip, torque between said engine and said load shaft lwhile generating heat proportional to slip therebetween, means eective to circulate a moving body of uid under pressure to the turbine drive working space of said device, and cooling means in-4 said member.

2. In a motor vehicle, an engine, a load shaft. a rotatable drum driven :by said engine .the exturbine clutchhaving elements housed within said drumfadapted to transmit variable torque between said engine and said load shaft, said eiements forming a vaned working space, means coupling said drumtoone of said turbine.'v clutch v elements, fluid pressure means adapted to circulate a'. moving body of iluid under pressure -in the space between the'said drum and said elements and circulate said body of fluid through clutch for transmitting the power of said engine with variable torque to said load shaft, a re-v said casing.

the working space-of said clutch, and aircircula- -tion means energised by lrotation of said engine effective to cool the moving body of fluid circula-tedvby said fluid pressure means in the said space between the said drum and said elements.

4 3. In cooling systems for fluid turbines adapted to transmit variable torque, an engine, a power shaft, driving mechanism arranged'to be driven by said shaft, a vaned uid turbine clutch coupling said shaft and said mechanism, a vaned working space between the elements of said clutch, a vdrum member driven directly by said engine coupled to one of said elements and enclosing said clutch, fluid-pressure circulating means arranged to maintain a body of fluid under pressure within said working space by delivery thereof to the confined space between said member and said clutch elements, a casing surrounding said elements and s aid member, directive vanes in said casing,` and airLV circulation means energised by rotation of said member withinsaid casing and Aguided by said directive vanes effective to' extract heat generated by the action voi.' said clutch insaid fluid by conduction through the material of said member.

4. A motorvehicle, an engine, a load shaft drive transmitting mechanism therebetween including a fluid turbine clutch having input and output elements', a drum surrounding said elements coupled to one of said elements and ro- 7.' In power transmitting devices, an engine, a load shaft, a clutch casing'structuresupported on said engine, a drum member within said structure, a clutch within said member for transmitting the power of the engine with variable torque vto said load shaft,embodyingcoacting turbine rotors vaned to form a fluid working space between them, one of said rotors being coupled to said engine by said member, a moving body of louvers in said structure opening in the normal direction of rotation of said drum for assisting the `ow of cooling air within the said casing.-

8. In motor ehicles, an engine, a load-shaft,

'- a variable speed transmission unit, a casing for 'tatable at varying speed ratios with respect to the other of said elements, a casing member located external to-said drum and exposed to air masses set 'in motion by the' movementof the,

` gine through coacting rotors said clutch having a vaned working space, a fluid body circulating within said drum and through said working space,'a variable speed transmission unit associated with said clutch, a casing for saidumt,

bearings for the driving elements of -said unit mounted in said casing, a fluid pressure circulation system foi said uid body comprising a pump driven 'by said engine, pressure passages l leading from said pump to the spacewithiu said drum and to the working space of said turbine clutch, pressurerelief passages leading therefrom to the bearings of said-unit, and the reservoir formed by the said casing wherein a temperature drop in the` said fluid body occurs, said pump utilizing the said casing-as a suction supply source, and means effective to, extract heat from said body of uid energised by rotation of engine and said .drum

' 6. Inotor vehicles, an engine, a load shaft, a clutch casing supported on said engine, a Ifluid material of said drum.

said unit comprising a fluid reservoir, a vaned fluid turbine drive device coupling said engine and said unit, said device havinga vaned work.

ing space, pump means effective to circulate a moving body of fluid from| said casing to said working space from whence said body passes to the bearings of said unit'l and returns to said casing, and cooling means in the line `of space adapted to cool said body of fluid heated by slip of said device, said means being driven by said engine.

' 9. In iiuid turbine :idrive devices, an engine, .a drum driven therebyla load shaft, a fluid reservoir, a fiuid circulating system communicating withsaid reservoir, a fluid turbine clutch adapted to couple said drum with said load shaft, and a moving body of uid in said system effective to fill the working space of said device while said engine is operating, also effective to transmit slip generated heat of said device to a rotating body of air set in motion by rotation of said drum,

byj'means of conduction through the wall section of saidrdrum.

10. In power devices for motor vehicles, an

engine, a load shaft, a drum driven by said engine, a fluid turbine clutch located within said drum and adapted to transmit the torque of the engine at variable slip ratios from said drum to said shaft, a Huid-chamber between said drum and said clutch, a vaned fluid working space included in said clutch, pump equipped circulation means effective tdcmaintain a moving body of uid under pressure in said chamber and flowing to said working space, said moving body of fluid being translated radially outward through saidchamber and inward to said working space to relief passages leading back to the suction side of said means, and' air circulation meansenergised by rotation of the said engine effective to extract heat from said fluid body through the l1. In motor vehicles, an engine, a mechanism driven by said engine embodyinga variable speed transmission unit associated with a fluid turbine clutch comprising dbacting rotors having a vaned uid working space, bearings Supporting said rotors and supporting the variable-speed elements l 4 iiow of y said `iiuid between said pump and said working of said unit, a fluid circulating system including lubrication passages for said rotor bearings and for said transmission bearings, lubricant circulation means effective to maintain a body of fluid under a constantly active pressure head in said working space and in the bearings for said rotor and in passages leadingl f-rom said working space to the bearings of said unit, a spent-pressure reservoir from which a pump draws iiuid to supply said system, and heat exchanging means effective to extract heat from said body of fluid in accordance with the speed of rotation of said engine.

12. In motor vehicles, an engine, a driving drum driven by said engine, a load shaft, a varia- -ble speed transmission unit, a fluid turbine clutch I having a vaned working space and coupling said shaft and said drum through said transmission unit at varying torques, a fluid circulation.

engine to said load shaft, said input rotor being operable at variable speed with respect to the speed of said engine, bearings for said shaft and said elements, duid pressure producing means 4for constantly providing working pressure to said clutch and to lubricate said bearings and said gear elements, a moving body of iluid circulated by said means for furnishing working uid to said clutch. and means' effective to extract the heat ofv friction generated by said clutch and by said bearings from said body of uid.

flow from said working space to said bearings of said unit at all times when said engine is rotating, and cooling means effective to extract heat from said iiuid body through the wall of said drum at all times when said engine is rotating.

13. In power devices, an engine, a load shaft,

to cool the said oil body by circulation of a moving column of airacross the external surface of said drum.

14. In power devices, an engine, a load shaft, gear elements associated with said load shaft, a fluid-turbine clutch having input and output rotors and adapted to transmit drive from said 15. In a motor vehicle, an engine, a load shaft,

a rotatable drum driven by said engine the external surface of which is exposed to air masses set in motion 'by operation of said engine, the internal surface of which is adapted to serve as a guide for a moving iilm of iiuid, a uid turbine clutch having elements housed within said drum,`

adapted to .transmit variable torque between said engine and said load shaft, said elements forming a vaned working space, means coupling said. drum to one of said turbine elements, fluid presing facing vaned turbine wheels enclosing a fluid working space, a drum driven by said engine enclosing saiddevice and driving one of said wheels, the inner surface of said drum affording a smooth flow surface for fluid under pressure flowing to said working space, a casing for said -device enclosing said drum, a removable closure Vrear of the transverse center plane of said device, and guide slots associated with said apertures related to the direction of rotation of said drum such that an air mass is drawn-into the .casing'from the forward apertures and ejected

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